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Abstract:

An apparatus provides micromechanical forces on a wound bed to accelerate
healing of a wound. The apparatus includes a pressure chamber having a
substantially airtight plunger and an inlet fluidly connected to a first
end of a conduit. A constant force spring is operatively connected to
apply a constant force to the plunger. A suction cup is in fluid
communication with a second end of the conduit.

Claims:

1. An apparatus for providing micromechanical forces on a wound bed to
accelerate healing of a wound, the apparatus comprising:a) a first
pressure chamber communicating with a first vacuum source and with a
suction cup;b) a second pressure chamber communicating with a second
vacuum source, the second pressure chamber being operably connected with
the first pressure chamber through a door; andc) a plunger in fluid
contact with the first chamber and operatively connected to the door,
wherein the plunger is configured and adapted to maintain a substantially
constant pressure in the first chamber by moving the door between:i) a
first position wherein the first and second chambers are in fluid
communication with one another; andii) a second position in which the
first and second chambers are in fluid isolation from one another.

2. An apparatus for providing micromechanical forces on a wound bed to
accelerate healing of a wound, the apparatus comprising:a) a first
pressure chamber communicating with a first vacuum source and with a
suction cup;b) a second pressure chamber communicating with a second
vacuum source, the second pressure chamber being operably connected with
the first pressure chamber through a door; andc) sensing and actuating
means configured and adapted to maintain a substantially constant
pressure in the first chamber by moving the door between:i) a first
position when the first pressure chamber is at an elevated pressure to
place the first and second chambers in fluid communication with one
another; andii) a second position in which the first and second chambers
are in fluid isolation from one another.

3. An apparatus for providing micromechanical forces on a wound bed to
accelerate healing of a wound, the apparatus comprising:a) a pressure
chamber including a substantially airtight plunger and an inlet fluidly
connected to a first end of a conduit;b) a constant force spring
operatively connected to apply a constant force to the plunger; andc) a
suction cup in fluid communication with a second end of the conduit.

4. An apparatus as recited in claim 3, further comprising a valve in the
conduit so as to be in fluid communication with the inlet of the pressure
chamber and with the suction cup, wherein the valve is configured and
adapted to be switched from:a) a first position in which the suction cup
is in fluid communication with the pressure chamber to apply a
substantially constant pressure to a wound bed within the suction cup;
andb) a second position in which the suction cup and the inlet of the
pressure chamber are in fluid isolation, and in which the inlet of the
pressure chamber can freely vent to the surroundings.

5. An apparatus as recited in claim 3, further comprising:a) a manifold in
the conduit in fluid communication with the pressure chamber; andb) a
pressure reserve in fluid communication with the manifold, wherein the
pressure reserve and manifold are configured and adapted to replenish the
pressure in the pressure chamber as needed to maintain a substantially
constant pressure in the pressure chamber.

6. An apparatus as recited in claim 3, wherein the constant force spring
is structured to act along a common axis of motion with the plunger.

7. An apparatus as recited in claim 3, further comprising pulley means
operatively connected to the plunger and to the constant force spring,
wherein the pulley means are configured and adapted to communicate forces
from the constant force spring acting along a first axis to the plunger
acting along a second axis.

8. An apparatus for generating constant cyclical micromechanical forces on
a wound bed to accelerate healing of a wound, the apparatus comprising:a)
a first pressure chamber configured and adapted to maintain a first
substantially constant pressure, the first pressure chamber including a
fluid inlet operatively connected to a manifold;b) a second pressure
chamber configured and adapted to maintain a second substantially
constant pressure, the second pressure chamber including a fluid inlet
operatively connected to the manifold; andc) a switching means
operatively connected with the manifold and fluidly connected to a
suction cup, the switching means being configured and adapted to
alternate fluid communication between the first and second pressure
chambers to apply an alternating pressure between the first and second
substantially constant pressures to the suction cup.

9. An apparatus as recited in claim 8, further comprising a self-winding
mechanical power source operatively connected to actuate the switching
means.

Description:

RELATED APPLICATION

[0001]This patent application claims the benefit of priority under 35
U.S.C. § 119 of U.S. Provisional Patent Application No. 61/041,952
filed on Apr. 3, 2008, the contents of which are incorporated herein by
reference.

FIELD OF THE INVENTION

[0002]The present invention relates to micromechanical force devices for
healing wounds, and more particularly, to devices for applying pressure
to accelerate healing of wounds.

DESCRIPTION OF RELATED ART

[0003]A variety of devices are known in the art for providing
micromechanical force therapy to wounds. Of such devices, many are
directed to devices that apply suction to wound beds to accelerate
healing of wounds. Exemplary wounds which can be treated with
micromechanical force therapy include diabetic foot ulcers, venous stasis
ulcers, pressure ulcers, traumatic wounds, surgical wounds, infected
wounds, burns, radiation wounds, wounds with exposed hardware, degloving
injuries, and venomous injuries. Typically, a wound is treated and
covered with an open cell foam. A drape, typically made of polyurethane
in the form of a suction cup, is placed over the foam. A vacuum source,
usually an electric pump, is connected to the suction cup to provide
constant or constant cycling pressure therapy to the wound bed. This
therapy can allow for a degree of healing of wounds in one or two days
that would normally require on the order of one month without the
therapy.

[0004]It is well known that cells respond to their chemical environment.
For example, different autocrine, paracrine, and endocrine molecules
travel to the wound bed to create the wound healing response. This
response is seen in changes in the gene expression profile of cells that
reside in the wound bed. However, the mechanical environment of the cell
(comprising both the mechanical state of the cell surroundings and
mechanical stimuli to the cell) also causes a change in the gene
expression profile of resident wound cells, thereby causing a response to
forces.

[0005]Generally, known devices used for applying micromechanical therapy
to wounds involve an electrical pump that is used to apply
sub-atmospheric pressure to a suction cup over the wound site. The pump
is typically bulky and the overall device limits mobility of individuals
undergoing micromechanical therapy.

[0006]Conventional methods and systems of providing micromechanical
therapy to wounds have generally been considered satisfactory for their
intended purpose. However, there remains an ever present need to advance
the state of the art for reducing the size, and increasing the mobility
and convenience of devices for applying micromechanical therapy. There
also remains a need in the art for devices and methods for providing
micromechanical therapy that are inexpensive and easy to make and use.
The present invention provides a solution for these problems.

SUMMARY OF THE INVENTION

[0007]In accordance with one aspect, the subject invention provides a new
and useful apparatus for providing micromechanical forces on a wound bed
to accelerate healing of a wound. The apparatus includes a first pressure
chamber communicating with a first vacuum source. The first pressure
chamber also communicates with a suction cup. A second pressure chamber
communicates with a second vacuum source. The second pressure chamber is
operably connected with the first pressure chamber through a door. A
plunger is in fluid contact with the first chamber and is operatively
connected to the door. The plunger is configured and adapted to maintain
a substantially constant pressure in the first chamber by moving the door
between a first position and a second position. In the first position,
and the first and second chambers are in fluid communication with one
another. In the second position, the first and second chambers are in
fluid isolation from one another.

[0008]In accordance with another embodiment, sensing and actuating means
are provided to maintain a substantially constant pressure in the first
chamber by moving the door between the first and second positions
described above. The sensing and actuating means can include any suitable
combination of electrical or mechanical sensors, control systems, motors,
and/or actuators.

[0009]The invention also provides an apparatus for providing
micromechanical forces on a wound bed to accelerate healing of a wound,
including a pressure chamber having a substantially airtight plunger and
an inlet fluidly connected to a first end of a conduit. A constant force
spring is operatively connected to apply a constant force to the plunger.
A suction cup is in fluid communication with a second end of the conduit.

[0010]A valve can be provided in the conduit so as to be in fluid
communication with the inlet of the pressure chamber and with the suction
cup. The valve can be configured and adapted to be switched from a first
position to a second position. In the first position, the suction cup is
in fluid communication with the pressure chamber to apply a substantially
constant pressure to a wound bed within the suction cup. In the second
position, the suction cup and the inlet of the pressure chamber are in
fluid isolation, and the inlet of the pressure chamber can freely vent to
the surroundings. The second position can be used to recharge the device
and/or remove fluids/liquids from the device.

[0011]In another embodiment, the apparatus further includes a manifold in
the conduit in fluid communication with the pressure chamber. In this
embodiment, a pressure reserve is in fluid communication with the
manifold. The pressure reserve and manifold can be configured and adapted
to replenish the pressure in the pressure chamber as needed to maintain a
substantially constant pressure in the pressure chamber.

[0012]The constant force spring can be structured to act along a common
axis of motion with the plunger. It is also contemplated that the
apparatus can include pulley means operatively connected to the plunger
and to the constant force spring. The pulley means can communicate forces
from the constant force spring acting along a first axis to the plunger
acting along a second axis. Any other suitable configuration for
providing a constant force from the spring to the plunger can also be
used.

[0013]In further accordance with the invention, an apparatus is provided
for generating constant cyclical micromechanical forces on a wound bed to
accelerate healing of a wound. The apparatus includes a first pressure
chamber configured and adapted to maintain a first substantially constant
pressure. The first pressure chamber includes a fluid inlet operatively
connected to the manifold. A second pressure chamber is configured and
adapted to maintain a second substantially constant pressure. The second
pressure chamber includes a fluid inlet and is operatively connected to
the manifold. Switching means are operatively connected with the manifold
and fluidly connected to a suction cup. The switching means are
configured and adapted to alternate fluid communication between the first
and second pressure chambers to apply a pressure to the suction cup that
alternates between the first and second substantially constant pressures.

[0014]The apparatus can further include a self-winding mechanical power
source operatively connected to actuate the switching means. The
switching means can also be powered by an electrical power source,
manually actuated power source, mechanical power source, or any other
suitable power source.

[0015]These and other features and benefits of the insert of the subject
invention and the manner of accelerating wound healing will become more
readily apparent to those having ordinary skill in the art from the
following enabling description of certain embodiments of the subject
invention taken in conjunction with the several drawings described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]So that those skilled in the art to which the subject invention
appertains will readily understand how to make and use the devices and
method for applying micromechanical therapy according to the subject
invention without undue experimentation, certain embodiments thereof will
be described in detail hereinbelow with reference to certain figures,
wherein:

[0017]FIG. 1 is a schematic view of a representative embodiment of an
apparatus for providing micromechanical forces on a wound bed in
accordance with the present invention, showing the first and second
chambers with a spring loaded plunger-actuated door for regulating
pressure therebetween;

[0018]FIG. 2 is a schematic view of another representative embodiment of
an apparatus for providing micromechanical forces on a wound bed in
accordance with the present invention, showing the sensing and actuating
means for moving the door to regulate pressures in the pressure chambers;

[0019]FIG. 3 is a perspective view of another representative embodiment of
an apparatus for providing micromechanical forces on a wound bed in
accordance with the present invention, showing a constant force spring
mounted to provide constant force to a pressure chamber and thereby
provide a constant pressure to a suction cup;

[0020]FIG. 4 is a perspective view of a portion of another representative
embodiment of an apparatus for providing micromechanical forces on a
wound bed in accordance with the present invention, showing a constant
force spring structure having a short axis configuration;

[0021]FIG. 5 is a perspective view of a portion of another representative
embodiment of an apparatus for providing micromechanical forces on a
wound bed in accordance with the present invention, showing a constant
force spring structure having a long axis configuration;

[0022]FIG. 6 is a perspective view of the apparatus of FIG. 4 in
accordance with the present invention, showing a manifold with a second
pressure chamber that provides a pressure reserve or pump for the main
pressure chamber;

[0023]FIG. 7 is a perspective view of the apparatus of FIG. 5 in
accordance with the present invention, showing a manifold with a second
pressure chamber that provides a pressure reserve or pump for the main
pressure chamber;

[0024]FIG. 8 is a perspective view of a portion of another representative
embodiment of an apparatus for providing micromechanical forces on a
wound bed in accordance with the present invention, showing a constant
force spring configured to act through a pulley structure on the plunger
of the pressure chamber;

[0025]FIG. 9 is a perspective view of a portion of the apparatus of FIG. 8
in accordance with the present invention, showing the pulley system,
constant force spring, and pressure chamber connected to a manifold with
a reserve pressure chamber;

[0026]FIG. 10 is a perspective view of the apparatus of FIG. 8 in
accordance with the present invention, showing the suction cup and
conduit connected to the manifold;

[0027]FIG. 11 is perspective view of a portion of the apparatus of FIG. 9
in accordance with the invention, next to a portion of the apparatus of
FIG. 4 in accordance with the present invention, showing the relative
size between the two embodiments;

[0028]FIG. 12 is a schematic view of a portion of a representative
embodiment of an apparatus for providing constant cyclical
micromechanical forces on a wound bed in accordance with the present
invention, showing the rotating valve assembly for alternating pressures
on a wound between a high pressure chamber and a low pressure chamber;
and

[0029]FIG. 13 is a schematic view of a portion of a representative
embodiment of an apparatus for providing micromechanical forces on a
wound bed in accordance with the invention, showing the stack of springs
connected to a gear chain for providing torque to the rotating valve
assembly of FIG. 12.

DETAILED DESCRIPTION OF A SPECIFIC EMBODIMENT

[0030]Referring now to the drawings, wherein like reference numerals
identify or otherwise refer to similar structural features or elements of
the various embodiments of the subject invention, there is illustrated in
FIG. 1 an exemplary apparatus for providing micromechanical forces on a
wound bed to accelerate healing of a wound designated generally by
reference character 100.

[0031]FIG. 1 shows an exemplary embodiment of an apparatus 100, which
includes a first pressure chamber 102 communicating with a first vacuum
source 104. The first pressure chamber also communicates with a suction
cup, which is not shown in the schematic view of FIG. 1, but see e.g.,
FIG. 3. A second pressure chamber 106 communicates with a second vacuum
source 108. The second pressure chamber 106 is operably connected with
the first pressure chamber 102 through a mechanical door 110. A plunger
112 is in fluid contact with the first chamber 102 on one side, and in
fluid contact with the surrounding atmosphere on the other side so as to
be moveable in reaction to changes of pressure in chamber 102. Plunger
112 is operatively connected to door 110. The plunger 112 is configured
and adapted to maintain a substantially constant pressure in the first
chamber 102 by moving the door between a first position and a second
position.

[0032]When starting the apparatus in operation, vacuum source 104, shown
as a syringe, can be drawn out to provide the desired level of vacuum in
chamber 102. This action will also simultaneously close door 110. When
door 110 is in the closed position, the first and second chambers are in
fluid isolation from one another. This allows for vacuum source 108, also
shown as a syringe, to be drawn out to provide an even greater level of
vacuum for chamber 106 than in chamber 102. It is preferable that the
initial pressure in chamber 106 be significantly lower than the initial
pressure in chamber 102, so that chamber 106 can act as an effectively
infinite vacuum when door 110 opens. Plunger 112 and door 110 are
configured to move in response to pressure changes in chamber 102, but to
be independent of the pressure in chamber 106. This allows chamber 106 to
be evacuated significantly below the treatment pressure in chamber 102,
which allows "storage" of vacuum pressure for use in maintaining the
treatment pressure in chamber 102.

[0033]Vacuum source 104 provides negative pressure or suction to the first
chamber 102, and in turn to a suction cup sealed to a wound bed. As the
wound bed drains into the suction cup, or as other pressure losses occur,
the pressure within first chamber 102 builds slightly. As the pressure
gradually builds in chamber 102, the building pressure acts on plunger
112 and moves plunger 112 in cooperation with the force provided by
spring 114. As plunger 112 moves outward, it slides door 110 in the same
direction until the port under door 110 is uncovered to allow fluid
communication between chamber 102 and chamber 106. This allows building
pressure from chamber 102 to be released into chamber 106.

[0034]As pressure is released from chamber 102 into chamber 106, the
pressure force acting inward on plunger 112 increases. As the increasing
inward pressure force overcomes the force of spring 114, plunger 112
moves back inward in chamber 102. Door 110 returns with plunger 112 until
the port between chambers 102 and 106 is sealed once again. At this
point, the treatment pressure is restored in chamber 102, and therefore
also at the wound bed in the suction cup.

[0035]The process repeats, as pressure is gradually lost again in chamber
102. Eventually the vacuum pressure in both chambers 106 and 108 will be
diminished and must be reset. With door 110 closed, chamber 106 can be
re-evacuated as needed without affecting the substantially constant
pressure at the wound bed. However, between charging of vacuum source
108, apparatus 100 operating in the manner described above maintains a
substantially constant pressure on the suction cup using only mechanical
feedback (no gages or electronic sensors) to control pressure.
Optionally, a simple modification can include a timer or sensor that
sounds an alarm when the device needs to be reset.

[0036]Spring 114 is preferably a variable force spring attached to a
structure 116 that allows for adjustment of the tension in spring 114 by
raising or lowering adjustment bolts 118. The spring tension can be set
in this manner to increase or decrease the constant pressure at the wound
bed as needed. Exemplary pressures include 125 mmHg, 150 mmHg, 175 mmHg,
or any other suitable pressure (these are absolute pressures where
atmospheric pressure is generally around 760 mmHg). A constant force
spring could optionally be used. However, the adjustability would be
limited.

[0037]While spring 114 provides the advantages of adjustability, those
skilled in the art will recognize that spring 114 is optional, as plunger
112 can be configured to have proper motion in response to the volumetric
changes in chamber 102 without a spring. For example, plunger 112 can be
connected to (or be part of) a pneumatic chamber in lieu of spring 114.
In short, any suitable spring means can be used without departing from
the spirit and scope of the invention.

[0038]Vacuum source 104 is also optional. When initializing apparatus 100
without vacuum source 104, vacuum source 108 evacuates chambers 102 and
106 together until door 110 closes, since by design door 110 is
configured to close when chamber 102 is at the desired treatment level.
Further pumping of source 108 after door 110 closes will lower the
pressure of chamber 106 below the treatment pressure without increasing
the suction on the wound bed beyond the treatment pressure.

[0039]Furthermore, any suitable mechanism can be used in lieu of spring
114, plunger 112, and door 110. It is possible to use any suitable relief
valve to regulate the treatment pressure. Moreover, any mechanism can be
used without departing from the spirit and scope of the invention as long
as it 1) cuts off fluid communication between the wound bed and the
pressure reserve when the wound bed drops to treatment pressure; 2)
allows further evacuation of the pressure reserve without further
lowering the pressure on the wound bed; and 3) brings the pressure
reserve back into fluid communication with the wound bed until treatment
pressure is restored at the wound bed if the pressure at the wound bed
rises above a tolerable threshold. In this manner, a substantially
constant pressure at the wound bed is maintained that oscillates only
between the desired treatment pressure and a tolerable pressure increase
above the desired pressure, which is required to move the mechanism to
restore the desired treatment pressure.

[0040]FIG. 2 shows apparatus 200 that is similar in most respects to the
apparatus 100 shown in FIG. 1. In lieu of using a pressure-actuated
plunger to move mechanical door 210 to regulate the pressure in chamber
202, an electrical control unit 212 is provided. Control unit 212
includes sensors, an actuator for moving door 210, and control system for
controlling door 210. Control unit 212 maintains a substantially constant
pressure in the first chamber 202 by moving the door between the first
and second positions described above. When control unit 212 senses the
pressure in chamber 202 has risen above a desired level, control unit 212
actuates door 210 to open the port between chambers 202 and 206 to
restore the proper pressure to chamber 202. Those skilled in the art will
readily appreciate that any suitable sensing and actuating means can be
used, including any suitable combination of electrical or mechanical
sensors, control systems, motors, and/or actuators.

[0041]FIG. 3 shows another apparatus 300 in accordance with the present
invention. Apparatus 300 includes a pressure chamber 302 having a
substantially airtight plunger 312 at one end. At the other end of
pressure chamber 302, a chamber inlet is fluidly connected to a first end
of a conduit 320. A constant force spring 314, mounted to a support
structure 316 is connected to plunger 312 to apply a constant force
thereto. A suction cup 322 is in fluid communication with a second end of
conduit 320. Grip 349 allows for manual resetting of plunger 312 when it
reaches its maximum extent of travel.

[0042]In operation, suction cup 322 is sealed to a wound bed with plunger
312 positioned near the inlet end of pressure chamber 302. As fluids
enter the system, which would otherwise raise the pressure in chamber
302, constant force spring 314 attached to a support structure 316 pulls
plunger 312 away from conduit 320. This action expands pressure chamber
302 to maintain a constant pressure. The constant spring force developed
by spring 314 controls the pressure levels maintained in pressure chamber
302 without any need for gages. Thus, the properties of spring 314 can be
varied by design, as is known in the art of constant force springs, in
order to create a particular pressure level for chamber 302.

[0043]FIG. 4 shows an apparatus 400 that is similar in most respects to
apparatus 300 described above. Spring 414 acts in the same axis of motion
as the movement of plunger 412. Apparatus 400 has a relatively short axis
of motion for spring 414. FIG. 5 shows a similar apparatus 500 having a
longer axis of motion for spring 514. Those skilled in the art will
readily appreciate that any length or configuration of spring can be used
as long as the force provided is substantially constant.

[0044]When plunger 512 has traveled to the end of its axis of motion, it
must be reset, e.g., manually, to maintain a substantially constant
negative pressure gradient at the wound bed. The short axis configuration
shown in FIG. 4 is advantageous because it is compact, and is well suited
to treatment of smaller wounds that heal quickly or have relatively low
amounts of fluid discharge. However, the longer axis configuration shown
in FIG. 5 provides longer duration of constant pressure before the
pressure needs resetting. Those skilled in the art will readily
appreciate that any suitable axis of motion length can be tailored for a
specific application without departing from the spirit and scope of the
invention.

[0045]As shown in FIG. 5, a valve 524 is provided in fluid communication
with pressure chamber 502 of apparatus 524. Valve 524 can be connected to
a conduit (e.g., 320 in FIG. 3) so as to be in fluid communication with
the inlet of pressure chamber 502 and with a suction cup (e.g., 322 in
FIG. 3). Valve 524 is configured to be switched from a first position to
a second position. In the first valve position, the suction cup is in
fluid communication with the pressure chamber to apply a substantially
constant pressure to a wound bed within the suction cup. In the second
position, the suction cup and the inlet of pressure chamber 502 are in
fluid isolation, and the inlet of pressure chamber 502 can freely vent to
the surroundings. A valve such as valve 524 could optionally be connected
to a fluid collection chamber so that if fluid has collected in the
pressure chamber, the fluid can be emptied into the collection chamber
when the vacuum is being re-applied, for example during dressing changes.
Those skilled in the art will appreciate that valve 524 is optional, and
moreover, any other suitable valve configuration can be used without
departing from the spirit and scope of the invention.

[0046]As shown in FIG. 6, apparatus 400 further includes a manifold 426 in
conduit 420 in fluid communication with pressure chamber 402 and suction
cup 422. In this embodiment, a pump or pressure reserve 406 is also
connected in fluid communication with manifold 426. Pressure chamber 402
and pressure reserve 406 connect to manifold 426 through valves 424a and
424b, similar to valve 524 described above. Pressure reserve 406 and
manifold 426 are configured to pump or recharge the vacuum pressure in
the pressure chamber 402 to maintain a substantially constant pressure in
suction cup 422. When spring 414 is near the end of its axis of travel,
pump/reserve 406 can be used in conjunction with valves 424a,b to pump
chamber 402 so spring 414 returns to the beginning of its axis of travel.
Pump 406 can be permanently attached to manifold 426, or can be
configured to attach to manifold 426 only when needed for pumping.

[0047]To pressurize apparatus 400, valve 424b can be rotated to place
pressure reserve 406 in fluid communication with chamber 402. Then the
plunger of pressure reserve 406 can withdrawn. Valve 424a can then be
rotated to vent to the atmosphere. Next, the plunger of pressure reserve
406 can be advanced back toward valve 424b to vent reserve 406 through
valve 424a, and valve 424a can be rotated to back to place chamber 402 in
fluid communication again with suction cup 422. These steps can be
repeated as needed to completely recharge pressure chamber 402 with
spring 414. FIG. 5 shows a similar configuration as that shown in FIG. 4,
having constant force spring 514, manifold 526, and reserve 506, with
long axis apparatus 500, in lieu of the short axis configuration shown in
FIG. 4.

[0048]The constant force spring can be structured to act along a common
axis of motion with the plunger, as described above. It is also
contemplated that the apparatus can include pulley means to communicate
forces from a constant force spring acting along a first axis to a
plunger acting along a second axis. Apparatus 800, shown in FIG. 8,
includes a pair of pulleys 828 that operatively connect plunger 812 to
spring 814 via cable 830. One pulley 828 is substantially in line with
the axis of motion of plunger 812. The other pulley 828 is offset to the
side of chamber 802 to be substantially in the line of motion of spring
814. In this configuration, constant force spring 814 can apply a
constant force to plunger 812 to supply a substantially constant pressure
to chamber 802 and conduit 820, much as described above, except that the
axis of motion of spring 814 is offset from the axis of motion of plunger
812.

[0049]This configuration is shorter in length and can be less bulky than
other configurations. For example, it is possible for apparatus 800 using
pulleys to provide the same long axis of motion as provided in long axis
configuration 500, while having a significantly shorter overall length of
the apparatus. Those skilled in the art will readily appreciate that any
other suitable configuration for providing a constant force from the
spring to the plunger can also be used without departing from the spirit
and scope of the invention.

[0050]As shown in FIGS. 9 and 10, apparatus 800 can be used in conjunction
with a manifold 826, pressure reserve 806, conduit 820, and suction cup
822 that work as described above with reference to FIGS. 6 and 7. FIG. 11
shows apparatus 800 next to apparatus 400 for a comparison of overall
length. Apparatus 800 is shorter in length than apparatus 400, while
having a longer axis of motion available, thus requiring less frequent
resetting to maintain pressure.

[0051]The force generated by a constant force spring in this application
must be matched to the plunger size and desired constant pressure for
wound therapy. Exemplary configurations include spring constants of
k=0.17 lbf, k=0.57 lbf, and k=0.97 lbf for pressure chambers (syringes)
of volumes V=3.0 cc, V=10.0 cc, and V=20.0 cc, having plunger areas of
A=0.07 in2, A=0.24 in2, and A=0.40 in2, respectively. Each
of these examples provides a therapy pressure of approximately P=125
mmHg.

[0052]It is advantageous for the apparatus to be actuated with one hand
when resetting pressures. Those skilled in the art will readily
appreciate how to use variations of the apparatus for use with
single-handed or double handed actuation without departing from the
spirit and scope of the invention.

[0053]While substantially constant negative pressure on a wound bed can
accelerate healing of the wound, it has also been proven that application
of negative pressures that vary in a repeated cycle can be even more
effective. FIG. 12 shows apparatus 900, which is configured to generate a
constant cyclical micromechanical force on a wound bed. Apparatus 900
includes a first pressure chamber 902 configured and adapted to maintain
a first substantially constant pressure level below atmospheric pressure,
much as the pressure chambers described above. First pressure chamber 902
includes a fluid inlet operatively connected to manifold 926. A second
pressure chamber 906 is configured and adapted to maintain a
substantially constant pressure that is even lower than the pressure of
chamber 902. The second pressure chamber includes a fluid inlet and is
operatively connected to the same manifold 926. A valve connected to
manifold 926 includes outer casing 924b containing rotating valve 924a
that alternates between high and low pressure chambers 902, 906 on one
end, while always being in fluid communication with the suction cup on
the other end.

[0054]Valve 924a thus provides for alternating fluid communication between
pressure chambers 902/906 and a suction cup (not shown, but see suction
cup 322 in FIG. 3). Valve 924a is configured to rotate within casing 924b
to position passage 924c in fluid communication with chambers 902 and 906
one at a time. The other end of passage 924c can be configured to
communicate with a suction cup at all times. Since the respective
pressures of chambers 902 and 906 are at different levels, as valve 924a
rotates, it provides a cyclical pressure variation between the first and
second pressure chambers to apply pressure to a wound bed that alternates
between two substantially constant levels. While shown as a circular
passage in the schematic of FIG. 12, passage 924c can be of any suitable
shape. For example, it is possible for passage 924c to have the shape of
a wedge (or a half solid interior) so that at exactly one pressure
chamber 902/906 is fluidly connected to the suction cup at a time.

[0055]If one pressure source, e.g., 906 is set to the extended position,
i.e. the plunger is pushed in, and the other pressure source, e.g. 902 is
set to the unextended position, i.e. the plunger is pulled out near its
maximum extent, and if passage 924c starts in communication with chamber
902, the wound will be at the pressure of chamber 902. As valve 924a
rotates, it will block chamber 902 off from the suction cup and bring
passage 924c into communication with chamber 906. Assuming for this
example that chamber 906 uses a constant force spring as described above
to provide a stronger vacuum than chamber 902, the plunger of chamber 906
will be drawn back by its spring to create increased suction at the wound
site.

[0056]Then, as valve 924a rotates back to connect passage 924c with
chamber 902, the plunger of chamber 902 will move toward valve 924a,
giving off some of its air to the wound, which was at the lower pressure
level of chamber 906. As valve 924a continues to rotate, the plungers of
chambers 902, 906 will move in the same manner, moving air from chamber
902 to chamber 906 little by little. As the process continues and as
pressure losses occur, one or more of the plungers will reach the end of
the respective pressure chamber. In order to maintain the treatment
pressure regime, the pressure chambers can be reset, as described above
with respect to constant pressure embodiments.

[0057]A standard stopcock can be adapted for use as a rotating valve. A
typical stopcock requires a constant torque of approximately 1.125 lbf-in
to rotate at a substantially constant rate of two seconds per cycle.
Using a spring motor with a 0.5-inch radius and an unwound length of 100
inches, an input torque of 63.3 lbf-in is necessary to rotate the
stopcock at this rate for about one hour. A gear box 951 (see FIG. 13)
allows reduction of the large torque to the desired 1.125 lbf-in needed
to drive the stopcock.

[0058]The following provides an explanation of how to design an exemplary
four-gear chain, as depicted in FIG. 13. Since the linear velocity
(rotational velocity times radius) of two gears (e.g., g1 and g2) at
their point of interaction is equal, the angular velocity of each gear
multiplied by its respective radius can be set equal to each other as
shown in equations the following equations:

ωg1rg1=ωg2rg2; and

ωg3rg3=ωg4rg4.

Linking gears 2 and 3 together will cause their angular velocities to be
equal to each other. The corresponding substitution and simplifications
result in:

ωg1=(rg2/rg1)(rg4/rg3)ωg4.

Using the same procedure used to determine this equation, multiplying the
force of each gear by its radius will determine the torque of the gear.
Since the torques for gears g2 and g3 are equal, a substitution can be
made again to give the following:

τg3=τg2; and

τg1=(rg1/rg2)(rg3/rg4)(1/eff1)(1/eff.sub-
.2)τg4,

where eff1 and eff2 are the efficiencies with which the torque
transfer takes place at the contacts of the two respective gears. To
determine the speed necessary for a spring motor to unwind in a specific
span of time, equation ν=2πrn/time was used, where r is the torque
spring radius and n is the number of windings. This time can also be
related to the angular velocity of the gears provided by:
time=2πn/ωg1. These equations allow for determination of
the spring torque required given required turning torque for the
stopcock, duration, and rate of turning. This allows generally for system
design given the input requirements.

[0059]Constant torque is preferable, in order to maintain a constant rate
of pressure cycling. To avoid using a much larger spring to achieve this
torque, the design shown in FIG. 13 uses 10 spring motors 914 in parallel
to provide the necessary torque. In this example, each spring motor has
an input torque of 6.5 lbf-in. However, those skilled in the art will
readily appreciate that this is exemplary only, and that any suitable
configuration can be used to supply the torque without departing from the
spirit and scope of the invention.

[0060]Those skilled in the art will readily appreciate that any suitable
structure for providing alternating connections to the two pressure
chambers can be used without departing from the spirit and scope of the
invention. Also, while apparatus 900 has been described as having two
substantially constant pressure sources, those skilled in the art will
readily appreciate that three or more pressure sources can be used
without departing from the spirit and scope of the invention.

[0061]Apparatus 900, can advantageously include a self-winding mechanical
power source to provide power to actuate rotating valve 924a. The
spring(s) 914 are linked on one side to gear chain 951 to provide
constant driving torque to valve 924a. On the other side spring(s) 914
are connected to a freely oscillating, weighted rotor through a
ratcheting mechanism to wind and tighten spring(s) 914 in response to
ordinary body movements, as is known in the art of self-winding
mechanisms.

[0062]When a patient wears apparatus 900, ordinary body movements, such as
walking, breathing, rolling over in sleep, etc., throughout the day can
provide power for the rotation of valve 924a, without needing to remember
to wind or charge any motors or batteries. This is similar to the manner
in which self-winding watches are powered by ordinary, routine motions of
the wearer's arm throughout the day. Those skilled in the art will
readily appreciate that self-winding mechanisms, while advantageous, are
optional. Electrical power sources, manually actuated power sources, foot
actuated power sources, mechanical power sources, or any other suitable
power sources can be used without departing from the spirit and scope of
the invention.

[0063]The various exemplary systems described above can provide pressure
for micromechanical therapy with a low-cost disposable alternative to the
known electrical pumps. This can potentially represent a cost to patients
that is as low as one-one-hundredth of the daily cost of the previously
available electrical pumps. Moreover, the hand-actuated embodiments
described above are highly portable and are convenient to use. Generally,
resetting of pressure chambers is only required once every 4-5 hours,
which can be performed by healthcare professionals in a hospital, or by a
patient not in a hospital.

[0064]The vacuum can be applied through the connection of another syringe
(see, e.g., FIGS. 6 and 7). By Pascal's Law, pressures are transmitted
equally within a fluid. Thus, to make the vacuum application user
friendly, which is particularly important for the very young or the
elderly, a small diameter syringe should be used. The forces are reduced
proportional to the cross section area of small diameter syringes.
Further implementations of this device can use a lever that is attached
to a syringe to allow for even more ease of use of the system.

[0065]In lieu of manually resetting the vacuums, the pressure chambers can
also be reset constantly through the use of body motions. For example, a
pump can be located under the padding in a shoe. This pump could apply a
negative pressure, with connected tubes communicating the negative
pressure from the foot to the application area each time the patient
takes a step. Similarly, other types of body motions, such as those that
occur when a person shifts while sleeping can also be taken advantage of
to implement the vacuum pressures. Such embodiments reduce or eliminate
the need for manual resetting of the pressure chambers, similar to the
way valve 924a, described above, can be powered with self-winding
mechanisms.

[0066]Known micromechanical therapy devices are heavy and cumbersome. One
known type of device provides a constant vacuum through the use of
weights applied to a syringe. The weights on this device have to be
consistent with the vacuums applied. In a typical configuration, the
necessary weights were approximately 2 kg (4.5 lbs). This is a
substantial weight to be carried around by a patient.

[0067]Other known types of micromechanical therapy devices use an
electronic pump to obtain the vacuum and keep that vacuum at a constant
level. Such devices are generally sold as a portable unit. Electrical
pump type devices are generally heavier than the embodiments of the
invention described above. Another large drawback of this type of device
is that the battery levels have to be monitored to know when a battery
needs to be replaced or recharged. Devices powered by electrical outlets
constrain the patient to remain near the power outlet. Further, if the
battery dies, the power fails, or the patient is in a situation where
power/batteries are unavailable (e.g. in the wilderness or battlefield),
the patient is in jeopardy of losing the treatment for that duration.

[0068]The embodiments of micromechanical therapy devices of the invention
are portable and relatively inexpensive because they do not require heavy
and expensive batteries. Convenient portability allows a patient to be
more mobile during the healing process, which also contributes to the
healing process. Further, the devices of the invention are less intrusive
and `imposing` which also makes recovery faster because of psychological
effects helping the patient feel less "sick" since he or she is not
hooked up to motors or other cumbersome devices. Moreover, the simplicity
of the invention allows for less monitoring by health care professionals
when used in a hospital setting. The devices in accordance with the
invention run less risk of electrocution and are also safer around
children than previously known devices, since little or no electrical
power is used (the power in the sensor embodiments, e.g., apparatus 200,
is a fraction of that used in the known devices that use power to operate
a large vacuum pump).

[0069]The devices in accordance with the invention can vary in size from a
few centimeters to a few inches. Thus they are relatively small compared
to known devices. One possible use of these devices is as bandages. The
wound healing devices of the invention can be used for different types of
wounds and cuts ranging from minor cuts to larger wounds. Since the
devices of the invention do not require batteries, they are much more
user friendly. Small size allows use as ubiquitous bandages replacing the
passive bandages that have been in use for so many years.

[0070]The invention can be used in the field by paramedics. Possible uses
include people who are camping or out in the wilderness where there is no
access to batteries or weights. Where there is a suitably trained
paramedic accompanying a group, the paramedic can use the device at his
or her discretion depending on the size of the wound. Other settings for
which the invention is well suited include application in athletics,
nursing homes, in veterinary clinics, and in research applications, such
as on animals for testing the efficacy and applicability of
micromechanical force therapy.

[0071]Another setting for which the devices of the invention are
particularly suited is in the battlefield. It is common for soldiers to
be treated with micromechanical force therapy. However, currently the
soldiers have to be flown in from the battlefield to the nearest hospital
where the known forms of micromechanical therapy devices (requiring a
wall vacuum outlet or an electronic vacuum generator) can be applied.
However, the devices in accordance with the invention can simply be
applied as a bandage.

[0072]The examples above have utilized syringes as pressure chambers.
However, those skilled in the art will readily appreciate that pistons,
bladders, or any other suitable pressure chambers can be used without
departing from the spirit and scope of the invention. Similarly, any
suitable pump can be used as a pressure reserve or vacuum source without
departing from the spirit and scope of the invention.

[0073]Although the apparatus and methods of the subject invention have
been shown and described with reference to certain embodiments, those
skilled in the art will readily appreciate that various changes and/or
modifications may be made thereto without departing from the spirit and
scope of the subject invention as defined by the appended claims.